This invention relates to recovery of the constituents of the poly(arylene sulfide) from reaction slurries. In accordance with one aspect of the invention it relates to the recovery of polar organic diluent from a poly(arylene sulfide) reaction mixture. In another aspect of the invention it relates to the evaporation of diluents from a mixture of reaction slurry with steam. In still another aspect of the invention it relates to the control of flows in a flash evaporation operation.
In one of its concepts, this invention relates to the evaporation of polar organic diluent from a mixture of a reaction effluent with steam added to reduce the dew point of the reaction diluent as an aid to evaporation. In another of its concepts, the invention relates to control of flows of reaction slurry and steam to produce an optimum evaporation mixture using steam dilution of a slurry.
In copending application Ser. No. 214,036, filed Dec. 30, 1971, now abandoned a method for removal of substantially all of the reaction diluent from a reaction mixture containing poly(arylene sulfide) polymer, organic polar diluent, byproduct alkali metal halide, and reaction slurry impurities is described. This method provides for mixing reactor effluent with high pressure steam and reducing the pressure of the mixture to atmospheric pressure in a flash tank. To best take advantage of the steam dilution evaporation techniques taught by the above-mentioned application, a method for controlling the amount of steam in relation to the polymer slurry is desirable. Although other control methods have been proposed for atmospheric, steam diluted, evaporation processes it has now been discovered that excellent results in diluent removal can be obtained by ratioing the steam dilution to the reactor effluent which is controlled by the amount of vapor leaving the flash zone in the evaporation process.
Accordingly, it is an object of this invention to provide an economical and effective method of control for the recovery of polar diluent from the reaction mixture of a poly(arylene sulfide) reaction using steam dilution of the reaction slurry. It is another object of this invention to provide a control system for the recovery of polar diluent from the reaction mixture of a poly(arylene sulfide) reaction using steam dilution.
Other aspects, objects and the several advantages of this invention will be apparent to one skilled in the art upon reading the specification and appended claims of this invention.